The Justice League is a team comprised of the premier superheroes of the DC Universe, making them "The Worlds Greatest Superheroes". The current incarnation of the League bears resemblance to the original Silver Age Justice League of America but features updated versions of its cast of characters for the DC Universe's current "New 52" continuity.

^^I believe this^^ Green Lantern was always more powerful than Superman because of his immense willpower and (at least for Kyle & Johnny) imagination, and physically the Flash can kill almost anyone. Martian Manhunter can put trillions of life-forms under his mental chains, faster than the Flash can say "Saw you in the shower".